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Author Topic: Mach 3 and C axis positioning/polar milling on Lathe  (Read 4730 times)

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Offline Monty

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Mach 3 and C axis positioning/polar milling on Lathe
« on: September 08, 2006, 10:54:51 PM »
Will mach 3 support using a vector drive AC spindle for positioning/polar milling?

I have a lathe I would like to implement this on. Planning to use the Grex to drive as yet undecided motor drives and the spindle.

The three strategies I have come up with in order of increasing complexity are:

1.) use the spindle motor with the appropriate vector drive and an encoder on the spindle

2.) use a separate servo motor to drive the spindle in milling mode (disengage main motor and vice versa)

3.) use a stepper or servo/harmonic drive with an electric clutch to drive the spindle in milling mode.



Option 1 gets the KISS award. I am a little concerned that a 3hp spindle motor will not have the low end torque to accomplish polar milling. It may work for positioning but will probably need a brake to hold position. I am limited by having a 230V single phase service to my shop. Otherwise I would just oversize the motor.

Option 2 would work, but the interlock setup is a bit dicey, and the smaller servo will be really zinging along at 2500 main spindle rpm.

Option 3 is the most trouble to implement, but it will work if Mach 3 will do it.


Any opinions? (not related to my mental state, please! ;D)
Re: Mach 3 and C axis positioning/polar milling on Lathe
« Reply #1 on: September 12, 2006, 10:46:53 AM »
2 and 3 are not a problem :)
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com

Offline Monty

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Re: Mach 3 and C axis positioning/polar milling on Lathe
« Reply #2 on: September 16, 2006, 10:46:17 PM »
Thanks for the reply Brian. I will post some pics of my lathe project and some additional info in the Projects section as soon as I get a chance. Right now I am planning to use the harmonic drive and clutch option.

One question I have is how does mach 3 treat constant surface speed?

Does it vary the feed rate only or the spindle speed and feed rate?

Of course it would be best if the spindle speed was varied as well as the feed rate, but if it isn't it gives me some more flexibility as to what type of spindle drive I use.

Thanks.

Monty
Re: Mach 3 and C axis positioning/polar milling on Lathe
« Reply #3 on: September 18, 2006, 08:20:13 AM »
The feedrate will not change as your spindle speed goes up... But if you are in Units/Min it will keep the correct "chip load" by changing the Units per min off feed rate to keep the feed per rev right... So to your question I think it is yes... (that was  a hard one)
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com